Method for transmitting a power headroom reporting in wireless communication system and a device therefor

ABSTRACT

The present invention relates to a wireless communication system. More specifically, the present invention relates to a method and a device for transmitting a power headroom reporting in wireless communication system, the method comprising: generating a PHR MAC CE including multiple PH fields for a serving cell; and transmitting the PHR MAC CE, wherein the PHR MAC CE includes an octet containing a single PCMAX field associated with the multiple PH fields for the serving cell

TECHNICAL FIELD

The present invention relates to a wireless communication system and,more particularly, to a method for transmitting a power headroomreporting in wireless communication system and a device therefor.

BACKGROUND ART

As an example of a mobile communication system to which the presentinvention is applicable, a 3rd Generation Partnership Project Long TermEvolution (hereinafter, referred to as LTE) communication system isdescribed in brief.

FIG. 1 is a view schematically illustrating a network structure of anEvolved Universal Mobile Telecommunications System (E-UMTS) as anexemplary radio communication system. The E-UMTS is an advanced versionof a conventional Universal Mobile Telecommunications System (UMTS) andbasic standardization thereof is currently underway in the 3GPP. E-UMTSmay be generally referred to as a Long Term Evolution (LTE) system. Thecommunication network is widely deployed to provide a variety ofcommunication services such as voice (VoIP) through IMS and packet data.

Referring to FIG. 1, the E-UMTS includes a User Equipment (UE), eNode Bs(eNBs), and an Access Gateway (AG) which is located at an end of thenetwork (E-UTRAN) and connected to an external network. The eNBs maysimultaneously transmit multiple data streams for a broadcast service, amulticast service, and/or a unicast service.

One or more cells may exist per eNB. The cell is set to operate in oneof bandwidths such as 1.25, 2.5, 5, 10, 15, and 20 MHz and provides adownlink (DL) or uplink (UL) transmission service to a plurality of UEsin the bandwidth. Different cells may be set to provide differentbandwidths. The eNB controls data transmission or reception to and froma plurality of UEs. The eNB transmits DL scheduling information of DLdata to a corresponding UE so as to inform the UE of a time/frequencydomain in which the DL data is supposed to be transmitted, coding, adata size, and hybrid automatic repeat and request (HARQ)-relatedinformation. In addition, the eNB transmits UL scheduling information ofUL data to a corresponding UE so as to inform the UE of a time/frequencydomain which may be used by the UE, coding, a data size, andHARQ-related information. An interface for transmitting user traffic orcontrol traffic may be used between eNBs. A core network (CN) mayinclude the AG and a network node or the like for user registration ofUEs. The AG manages the mobility of a UE on a tracking area (TA) basis.One TA includes a plurality of cells.

Although wireless communication technology has been developed to LTE andNR based on wideband code division multiple access (WCDMA), the demandsand expectations of users and service providers are on the rise. Inaddition, considering other radio access technologies under development,new technological evolution is required to secure high competitivenessin the future. Decrease in cost per bit, increase in serviceavailability, flexible use of frequency bands, a simplified structure,an open interface, appropriate power consumption of UEs, and the likeare required.

As more and more communication devices demand larger communicationcapacity, there is a need for improved mobile broadband communicationcompared to existing RAT. Also, massive machine type communication(MTC), which provides various services by connecting many devices andobjects, is one of the major issues to be considered in the nextgeneration communication (NR, New Radio). In addition, a communicationsystem design considering a service/UE sensitive to reliability andlatency is being discussed. The introduction of next-generation RAT,which takes into account such Enhanced Mobile BroadBand (eMBB)transmission, and ultra-reliable and low latency communication (URLLC)transmission, is being discussed.

DISCLOSURE Technical Problem

An object of the present invention devised to solve the problem lies ina method and device for transmitting a power headroom reporting inwireless communication system.

In LTE, the Power Headroom Reporting (PHR) procedure is used to providethe serving eNB with information about the difference between thenominal UE maximum transmit power and the estimated power for UL-SCHtransmission and also with information about the difference between thenominal UE maximum power and the estimated power for UL-SCH and PUCCHtransmission on SpCell and PUCCH SCell. And the eNB can use the PHRreport as input to the scheduler. Based on the available power headroomthe scheduler will decide a suitable number of PRBs and an appropriateMCS as well a correct transmit power adjustment.

In Rel-15, NR system supports the wider bandwidth (WB) or multi-beamoperation.

The carrier performing the wider bandwidth operation can be composed ofone or more bandwidth part(s) and each bandwidth part is associated witha specific numerology. In this operation, gNB can configure or activatea specific bandwidth part for a UE. According to the current RAN1agreement, UE expects at least one DL bandwidth part and one ULbandwidth part being active among the set of configured bandwidth partsfor a given time instant. In addition, for a single carrier WB UE,multiple active bandwidth parts with different numerologies can beconfigured for a UE simultaneously. In this WB operation, the gNB mayrequire PH information per BWP in order to decide a suitable UL resourceof a UE.

Further, to provide link robustness between UE and gNB for both downlinkand uplink, there may be multiple beam pair links between UE and gNB,where a beam pair link comprises a UE TX beam and a gNB RX beam. Byusing the multiple beam pair links, the UE may be able to transmit orreceive a data repeatedly, if necessary. RAN1 agreed that UE should beable to maintain links with multiple DL beam pair of one cell betweenmultiple TRPs and the UE. For UL link robustness, it would be necessaryto maintain multiple UL beam pair links between multiple TRPs and theUE. In particular, pathloss between multiple TRPs may be significantlydifferent than pathloss in multiple links within a single TRP due totheir locations. This may result in different resource allocations e.g.,including transmit power, between multiple beam pair links.

The gNB should allocate the suitable UL resource for each beam pairbased on the UE's PH information.

The technical problems solved by the present invention are not limitedto the above technical problems and those skilled in the art mayunderstand other technical problems from the following description.

Technical Solution

The object of the present invention can be achieved by providing amethod for User Equipment (UE) operating in a wireless communicationsystem as set forth in the appended claims.

In another aspect of the present invention, provided herein is acommunication apparatus as set forth in the appended claims.

It is to be understood that both the foregoing general description andthe following detailed description of the present invention areexemplary and explanatory and are intended to provide furtherexplanation of the invention as claimed.

Advantageous Effects

This invention proposes to define a new PHR trigger event and a new PHRMAC CE format in order for a UE to transmit a PH information for a beampair (BP) or bandwidth part (BWP) when a UE operates in multi-beam orwider bandwidth operation.

This invention proposes that a UE transmits one or more PH(s) for asingle P_(CMAX) field in a PHR MAC CE in order to inform each PH fordifferent UL beam pair or different numerology/bandwidth part of aserving cell.

It will be appreciated by persons skilled in the art that the effectsachieved by the present invention are not limited to what has beenparticularly described hereinabove and other advantages of the presentinvention will be more clearly understood from the following detaileddescription taken in conjunction with the accompanying drawings.

DESCRIPTION OF DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this application, illustrate embodiment(s) of the invention andtogether with the description serve to explain the principle of theinvention.

FIG. 1 is a diagram showing a network structure of an Evolved UniversalMobile Telecommunications System (E-UMTS) as an example of a wirelesscommunication system;

FIG. 2a is a block diagram illustrating network structure of an evolveduniversal mobile telecommunication system (E-UMTS), and FIG. 2b is ablock diagram depicting architecture of a typical E-UTRAN and a typicalEPC;

FIG. 3 is a diagram showing a control plane and a user plane of a radiointerface protocol between a UE and an E-UTRAN based on a 3rd generationpartnership project (3GPP) radio access network standard;

FIG. 4a is a block diagram illustrating network structure of NG RadioAccess Network (NG-RAN) architecture, and FIG. 4b is a block diagramdepicting architecture of functional Split between NG-RAN and 5G CoreNetwork (5GC);

FIG. 5 is a diagram showing a control plane and a user plane of a radiointerface protocol between a UE and a NG-RAN based on a 3rd generationpartnership project (3GPP) radio access network standard;

FIG. 6 is a block diagram of a communication apparatus according to anembodiment of the present invention;

FIG. 7 is a diagram for signaling of power headroom reporting via a MACCE;

FIG. 8a is examples for multiple beam pair links, and FIG. 8b is anexample of PHR trigger in BWP activation/deactivation;

FIG. 9 is a conceptual diagram for transmitting a power headroomreporting in wireless communication system according to embodiments ofthe present invention;

FIG. 10 is an example of PHR trigger based on the BWP configuration; and

FIGS. 11 to 14 are examples for a PHR MAC CE for BP or BWP operationaccording to embodiments of the present invention.

BEST MODE

Universal mobile telecommunications system (UMTS) is a 3rd Generation(3G) asynchronous mobile communication system operating in wideband codedivision multiple access (WCDMA) based on European systems, globalsystem for mobile communications (GSM) and general packet radio services(GPRS). The long-term evolution (LTE) of UMTS is under discussion by the3rd generation partnership project (3GPP) that standardized UMTS.

The 3GPP LTE is a technology for enabling high-speed packetcommunications. Many schemes have been proposed for the LTE objectiveincluding those that aim to reduce user and provider costs, improveservice quality, and expand and improve coverage and system capacity.The 3G LTE requires reduced cost per bit, increased serviceavailability, flexible use of a frequency band, a simple structure, anopen interface, and adequate power consumption of a terminal as anupper-level requirement.

Hereinafter, structures, operations, and other features of the presentinvention will be readily understood from the embodiments of the presentinvention, examples of which are illustrated in the accompanyingdrawings. Embodiments described later are examples in which technicalfeatures of the present invention are applied to a 3GPP system.

Although the embodiments of the present invention are described using along term evolution (LTE) system and a LTE-advanced (LTE-A) system inthe present specification, they are purely exemplary. Therefore, theembodiments of the present invention are applicable to any othercommunication system corresponding to the above definition. In addition,although the embodiments of the present invention are described based ona frequency division duplex (FDD) scheme in the present specification,the embodiments of the present invention may be easily modified andapplied to a half-duplex FDD (H-FDD) scheme or a time division duplex(TDD) scheme.

FIG. 2a is a block diagram illustrating network structure of an evolveduniversal mobile telecommunication system (E-UMTS). The E-UMTS may bealso referred to as an LTE system. The communication network is widelydeployed to provide a variety of communication services such as voice(VoIP) through IMS and packet data.

As illustrated in FIG. 2a , the E-UMTS network includes an evolved UMTSterrestrial radio access network (E-UTRAN), an Evolved Packet Core (EPC)and one or more user equipment. The E-UTRAN may include one or moreevolved NodeB (eNodeB) 20, and a plurality of user equipment (UE) 10 maybe located in one cell. One or more E-UTRAN mobility management entity(MME)/system architecture evolution (SAE) gateways 30 may be positionedat the end of the network and connected to an external network.

As used herein, “downlink” refers to communication from eNodeB 20 to UE10, and “uplink” refers to communication from the UE to an eNodeB. UE 10refers to communication equipment carried by a user and may be alsoreferred to as a mobile station (MS), a user terminal (UT), a subscriberstation (SS) or a wireless device.

FIG. 2b is a block diagram depicting architecture of a typical E-UTRANand a typical EPC.

As illustrated in FIG. 2b , an eNodeB 20 provides end points of a userplane and a control plane to the UE 10. MME/SAE gateway 30 provides anend point of a session and mobility management function for UE 10. TheeNodeB and MME/SAE gateway may be connected via an S1 interface.

The eNodeB 20 is generally a fixed station that communicates with a UE10, and may also be referred to as a base station (BS) or an accesspoint. One eNodeB 20 may be deployed per cell. An interface fortransmitting user traffic or control traffic may be used between eNodeBs20.

The MME provides various functions including NAS signaling to eNodeBs20, NAS signaling security, AS Security control, Inter CN node signalingfor mobility between 3GPP access networks, Idle mode UE Reachability(including control and execution of paging retransmission), TrackingArea list management (for UE in idle and active mode), PDN GW andServing GW selection, MME selection for handovers with MME change, SGSNselection for handovers to 2G or 3G 3GPP access networks, Roaming,Authentication, Bearer management functions including dedicated bearerestablishment, Support for PWS (which includes ETWS and CMAS) messagetransmission. The SAE gateway host provides assorted functions includingPer-user based packet filtering (by e.g. deep packet inspection), LawfulInterception, UE IP address allocation, Transport level packet markingin the downlink, UL and DL service level charging, gating and rateenforcement, DL rate enforcement based on APN-AMBR. For clarity MME/SAEgateway 30 will be referred to herein simply as a “gateway,” but it isunderstood that this entity includes both an MME and an SAE gateway.

A plurality of nodes may be connected between eNodeB 20 and gateway 30via the S1 interface. The eNodeBs 20 may be connected to each other viaan X2 interface and neighboring eNodeBs may have a meshed networkstructure that has the X2 interface.

As illustrated, eNodeB 20 may perform functions of selection for gateway30, routing toward the gateway during a Radio Resource Control (RRC)activation, scheduling and transmitting of paging messages, schedulingand transmitting of Broadcast Channel (BCCH) information, dynamicallocation of resources to UEs 10 in both uplink and downlink,configuration and provisioning of eNodeB measurements, radio bearercontrol, radio admission control (RAC), and connection mobility controlin LTE ACTIVE state. In the EPC, and as noted above, gateway 30 mayperform functions of paging origination, LTE-IDLE state management,ciphering of the user plane, System Architecture Evolution (SAE) bearercontrol, and ciphering and integrity protection of Non-Access Stratum(NAS) signaling.

The EPC includes a mobility management entity (MME), a serving-gateway(S-GW), and a packet data network-gateway (PDN-GW). The MME hasinformation about connections and capabilities of UEs, mainly for use inmanaging the mobility of the UEs. The S-GW is a gateway having theE-UTRAN as an end point, and the PDN-GW is a gateway having a packetdata network (PDN) as an end point.

FIG. 3 is a diagram showing a control plane and a user plane of a radiointerface protocol between a UE and an E-UTRAN based on a 3GPP radioaccess network standard. The control plane refers to a path used fortransmitting control messages used for managing a call between the UEand the E-UTRAN. The user plane refers to a path used for transmittingdata generated in an application layer, e.g., voice data or Internetpacket data.

A physical (PHY) layer of a first layer provides an information transferservice to a higher layer using a physical channel. The PHY layer isconnected to a medium access control (MAC) layer located on the higherlayer via a transport channel. Data is transported between the MAC layerand the PHY layer via the transport channel. Data is transported betweena physical layer of a transmitting side and a physical layer of areceiving side via physical channels. The physical channels use time andfrequency as radio resources. In detail, the physical channel ismodulated using an orthogonal frequency division multiple access (OFDMA)scheme in downlink and is modulated using a single carrier frequencydivision multiple access (SC-FDMA) scheme in uplink.

The MAC layer of a second layer provides a service to a radio linkcontrol (RLC) layer of a higher layer via a logical channel. The RLClayer of the second layer supports reliable data transmission. Afunction of the RLC layer may be implemented by a functional block ofthe MAC layer. A packet data convergence protocol (PDCP) layer of thesecond layer performs a header compression function to reduceunnecessary control information for efficient transmission of anInternet protocol (IP) packet such as an IP version 4 (IPv4) packet oran IP version 6 (IPv6) packet in a radio interface having a relativelysmall bandwidth.

A radio resource control (RRC) layer located at the bottom of a thirdlayer is defined only in the control plane. The RRC layer controlslogical channels, transport channels, and physical channels in relationto configuration, re-configuration, and release of radio bearers (RBs).An RB refers to a service that the second layer provides for datatransmission between the UE and the E-UTRAN. To this end, the RRC layerof the UE and the RRC layer of the E-UTRAN exchange RRC messages witheach other.

One cell of the eNB is set to operate in one of bandwidths such as 1.25,2.5, 5, 10, 15, and 20 MHz and provides a downlink or uplinktransmission service to a plurality of UEs in the bandwidth. Differentcells may be set to provide different bandwidths.

Downlink transport channels for transmission of data from the E-UTRAN tothe UE include a broadcast channel (BCH) for transmission of systeminformation, a paging channel (PCH) for transmission of paging messages,and a downlink shared channel (SCH) for transmission of user traffic orcontrol messages. Traffic or control messages of a downlink multicast orbroadcast service may be transmitted through the downlink SCH and mayalso be transmitted through a separate downlink multicast channel (MCH).

Uplink transport channels for transmission of data from the UE to theE-UTRAN include a random access channel (RACH) for transmission ofinitial control messages and an uplink SCH for transmission of usertraffic or control messages. Logical channels that are defined above thetransport channels and mapped to the transport channels include abroadcast control channel (BCCH), a paging control channel (PCCH), acommon control channel (CCCH), a multicast control channel (MCCH), and amulticast traffic channel (MTCH).

FIG. 4a is a block diagram illustrating network structure of NG RadioAccess Network (NG-RAN) architecture, and FIG. 4b is a block diagramdepicting architecture of functional Split between NG-RAN and 5G CoreNetwork (5GC).

An NG-RAN node is a gNB, providing NR user plane and control planeprotocol terminations towards the UE, or an ng-eNB, providing E-UTRAuser plane and control plane protocol terminations towards the UE.

The gNBs and ng-eNBs are interconnected with each other by means of theXn interface. The gNBs and ng-eNBs are also connected by means of the NGinterfaces to the 5GC, more specifically to the AMF (Access and MobilityManagement Function) by means of the NG-C interface and to the UPF (UserPlane Function) by means of the NG-U interface.

The Xn Interface includes Xn user plane (Xn-U), and Xn control plane(Xn-C). The Xn User plane (Xn-U) interface is defined between two NG-RANnodes. The transport network layer is built on IP transport and GTP-U isused on top of UDP/IP to carry the user plane PDUs. Xn-U providesnon-guaranteed delivery of user plane PDUs and supports the followingfunctions: i) Data forwarding, and ii) Flow control. The Xn controlplane interface (Xn-C) is defined between two NG-RAN nodes. Thetransport network layer is built on SCTP on top of IP. The applicationlayer signalling protocol is referred to as XnAP (Xn ApplicationProtocol). The SCTP layer provides the guaranteed delivery ofapplication layer messages. In the transport IP layer point-to-pointtransmission is used to deliver the signalling PDUs. The Xn-C interfacesupports the following functions: i) Xn interface management, ii) UEmobility management, including context transfer and RAN paging, and iii)Dual connectivity.

The NG Interface includes NG User Plane (NG-U) and NG Control Plane(NG-C). The NG user plane interface (NG-U) is defined between the NG-RANnode and the UPF. The transport network layer is built on IP transportand GTP-U is used on top of UDP/IP to carry the user plane PDUs betweenthe NG-RAN node and the UPF. NG-U provides non-guaranteed delivery ofuser plane PDUs between the NG-RAN node and the UPF.

The NG control plane interface (NG-C) is defined between the NG-RAN nodeand the AMF. The transport network layer is built on IP transport. Forthe reliable transport of signalling messages, SCTP is added on top ofIP. The application layer signalling protocol is referred to as NGAP (NGApplication Protocol). The SCTP layer provides guaranteed delivery ofapplication layer messages. In the transport, IP layer point-to-pointtransmission is used to deliver the signalling PDUs.

NG-C provides the following functions: i) NG interface management, ii)UE context management, iii) UE mobility management, iv) ConfigurationTransfer, and v) Warning Message Transmission.

The gNB and ng-eNB host the following functions: i) Functions for RadioResource Management: Radio Bearer Control, Radio Admission Control,Connection Mobility Control, Dynamic allocation of resources to UEs inboth uplink and downlink (scheduling), ii) IP header compression,encryption and integrity protection of data, iii) Selection of an AMF atUE attachment when no routing to an AMF can be determined from theinformation provided by the UE, iv) Routing of User Plane data towardsUPF(s), v) Routing of Control Plane information towards AMF, vi)Connection setup and release, vii) Scheduling and transmission of pagingmessages (originated from the AMF), viii) Scheduling and transmission ofsystem broadcast information (originated from the AMF or O&M), ix)Measurement and measurement reporting configuration for mobility andscheduling, x) Transport level packet marking in the uplink, xi) SessionManagement, xii) Support of Network Slicing, and xiii) QoS Flowmanagement and mapping to data radio bearers. The Access and MobilityManagement Function (AMF) hosts the following main functions: i) NASsignalling termination, ii) NAS signalling security, iii) AS Securitycontrol, iv) Inter CN node signalling for mobility between 3GPP accessnetworks, v) Idle mode UE Reachability (including control and executionof paging retransmission), vi) Registration Area management, vii)Support of intra-system and inter-system mobility, viii) AccessAuthentication, ix) Mobility management control (subscription andpolicies), x) Support of Network Slicing, and xi) SMF selection.

The User Plane Function (UPF) hosts the following main functions: i)Anchor point for Intra-/Inter-RAT mobility (when applicable), ii)External PDU session point of interconnect to Data Network, iii) Packetinspection and User plane part of Policy rule enforcement, iv) Trafficusage reporting, v) Uplink classifier to support routing traffic flowsto a data network, vi) QoS handling for user plane, e.g. packetfiltering, gating, UL/DL rate enforcement, and vii) Uplink Trafficverification (SDF to QoS flow mapping).

The Session Management function (SMF) hosts the following mainfunctions: i) Session Management, ii) UE IP address allocation andmanagement, iii) Selection and control of UP function, iv) Configurestraffic steering at UPF to route traffic to proper destination, v)Control part of policy enforcement and QoS, vi) Downlink DataNotification.

FIG. 5 is a diagram showing a control plane and a user plane of a radiointerface protocol between a UE and a NG-RAN based on a 3rd generationpartnership project (3GPP) radio access network standard.

The user plane protocol stack contains Phy, MAC, RLC, PDCP and SDAP(Service Data Adaptation Protocol) which is newly introduced to support5G QoS model.

The main services and functions of SDAP entity include i) Mappingbetween a QoS flow and a data radio bearer, and ii) Marking QoS flow ID(QFI) in both DL and UL packets. A single protocol entity of SDAP isconfigured for each individual PDU session.

At the reception of an SDAP SDU from upper layer for a QoS flow, thetransmitting SDAP entity may map the SDAP SDU to the default DRB ifthere is no stored QoS flow to DRB mapping rule for the QoS flow. Ifthere is a stored QoS flow to DRB mapping rule for the QoS flow, theSDAP entity may map the SDAP SDU to the DRB according to the stored QoSflow to DRB mapping rule. And the SDAP entity may construct the SDAP PDUand deliver the constructed SDAP PDU to the lower layers.

FIG. 6 is a block diagram of a communication apparatus according to anembodiment of the present invention.

The apparatus shown in FIG. 6 can be a user equipment (UE) and/or eNB orgNB adapted to perform the above mechanism, but it can be any apparatusfor performing the same operation.

As shown in FIG. 6, the apparatus may comprises a DSP/microprocessor(110) and RF module (transceiver; 135). The DSP/microprocessor (110) iselectrically connected with the transceiver (135) and controls it. Theapparatus may further include power management module (105), battery(155), display (115), keypad (120), SIM card (125), memory device (130),speaker (145) and input device (150), based on its implementation anddesigner's choice.

Specifically, FIG. 6 may represent a UE comprising a receiver (135)configured to receive a request message from a network, and atransmitter (135) configured to transmit the transmission or receptiontiming information to the network. These receiver and the transmittercan constitute the transceiver (135). The UE further comprises aprocessor (110) connected to the transceiver (135: receiver andtransmitter).

Also, FIG. 6 may represent a network apparatus comprising a transmitter(135) configured to transmit a request message to a UE and a receiver(135) configured to receive the transmission or reception timinginformation from the UE. These transmitter and receiver may constitutethe transceiver (135). The network further comprises a processor (110)connected to the transmitter and the receiver. This processor (110) maybe configured to calculate latency based on the transmission orreception timing information.

FIG. 7 is a diagram for signaling of power headroom reporting via a MACCE.

The amount of transmission power available in each UE is also relevantfor the uplink scheduler. Obviously, there is little reason to schedulea higher data rate than the available transmission power can support. Inthe downlink, the available power is immediately known to the scheduleras the power amplifier is located in the same node as the scheduler. Forthe uplink, the power availability, or power headroom is defined as thedifference between the nominal maximum output power and the estimatedoutput power for UL-SCH transmission.

This quantity can be positive as well as negative (on a dB scale), wherea negative value would indicate that the network has scheduled a higherdata rate than the terminal can support given its current poweravailability. The power headroom depends on the power-control mechanismand thereby indirectly on factors such as the interference in the systemand the distance to the base stations. Information about the powerheadroom is fed back from the terminals to the eNodeB in a similar wayas the buffer-status reports—that is, only when the terminal isscheduled to transmit on the UL-SCH.

A Power Headroom Report (PHR) shall be triggered if any of the followingevents occur: i) prohibitPHR-Timer expires or has expired and the pathloss has changed more than dl-PathlossChange dB for at least oneactivated Serving Cell of any MAC entity which is used as a pathlossreference since the last transmission of a PHR in this MAC entity whenthe MAC entity has UL resources for new transmission; ii)periodicPHR-Timer expires; iii) upon configuration or reconfiguration ofthe power headroom reporting functionality by upper layers, which is notused to disable the function; iv) activation of an SCell of any MACentity with configured uplink, v) addition of the PSCell, vi)prohibitPHR-Timer expires or has expired, when the MAC entity has ULresources for new transmission, and the following is true in this TTIfor any of the activated Serving Cells of any MAC entity with configureduplink: there are UL resources allocated for transmission or there is aPUCCH transmission on this cell, and the required power backoff due topower management for this cell has changed more than dl-PathlossChangedB since the last transmission of a PHR when the MAC entity had ULresources allocated for transmission or PUCCH transmission on this cell.

It is also possible to configure a prohibit timer to control the minimumtime between two power-headroom reports and thereby the signaling loadon the uplink.

If the MAC entity has UL resources allocated for new transmission forthis TTI the MAC entity shall start periodicPHR-Timer if it is the firstUL resource allocated for a new transmission since the last MAC reset.If the Power Headroom reporting procedure determines that at least onePHR has been triggered and not cancelled, the MAC entity shall obtainthe value of the Type 1 power headroom from the physical layer, andinstruct the Multiplexing and Assembly procedure to generate andtransmit a PHR MAC control element based on the value reported by thephysical layer. And the MAC entity start or restart periodicPHR-Timer,start or restart prohibitPHR-Timer, and cancel all triggered PHR.

For the uplink transmission, the UE uses the PHR in order to provide thenetwork with information about the difference between the nominalmaximum transmit power and the estimated required transmit power. Thus,PHR indicates how much transmission power can be additionally used fromthe UE side.

In LTE, the Power Headroom Report (PHR) MAC control element isidentified by a MAC PDU subheader with LCID as specified in Table 1. Ithas a fixed size and consists of a single octet defined as follows (FIG.7a ):

TABLE 1 Index LCID values 00000 CCCH 00001-01010 Identity of the logicalchannel 01011 CCCH 01100 CCCH 01101-10011 Reserved 10100 Recommended bitrate query 10101 SPS confirmation 10110 Truncated Sidelink BSR 10111Sidelink BSR 11000 Dual Connectivity Power Headroom Report 11001Extended Power Headroom Report 11010 Power Headroom Report 11011 C-RNTI11100 Truncated BSR 11101 Short BSR 11110 Long BSR 11111 Padding

‘R’ is reserved bit, set to “0”;

Power Headroom (PH) field indicates the power headroom level. The lengthof the field is 6 bits. The reported PH and the corresponding powerheadroom levels are shown in Table 2;

TABLE 2 PH Power Headroom Level 0 POWER_HEADROOM_0 1 POWER_HEADROOM_1 2POWER_HEADROOM_2 3 POWER_HEADROOM_3 . . . . . . 60 POWER_HEADROOM_60 61POWER_HEADROOM_61 62 POWER_HEADROOM_62 63 POWER_HEADROOM_63

For extendedPHR, the Extended Power Headroom Report (PHR) MAC controlelement is identified by a MAC PDU subheader with LCID as specified inTable 1. It has a variable size and is defined in FIGS. 7b and 7c . WhenType 2 PH is reported, the octet containing the Type 2 PH field isincluded first after the octet indicating the presence of PH per SCelland followed by an octet containing the associated P_(CMAX,c) field (ifreported). Then follows an octet with the Type 1 PH field and an octetwith the associated P_(CMAX,c) field (if reported), for the PCell. Andthen follows in ascending order based on the ServCelllndex an octet withthe Type x PH field, wherein x is equal to 3 when theul-Configuration-r14 is configured for this SCell, x is equal to 1otherwise, and an octet with the associated P_(CMAX,c) field (ifreported), for each SCell indicated in the bitmap.

When the highest SCellIndex of SCell with configured uplink is less than8, one octet with C fields is used for indicating the presence of PH perSCell (FIG. 7b ), Otherwise, four octets are used (FIG. 7c ).

The UE determines whether PH value for an activated Serving Cell isbased on real transmission or a reference format by considering thedownlink control information which has been received until and includingthe PDCCH occasion in which the first UL grant is received since a PHRhas been triggered.

FIG. 7b is an example for Extended PHR MAC Control Elements with thehighest SCelllndex of SCell with configured uplink is less than 8, andFIG. 7c is an example for Extended PHR MAC Control Elements with thehighest SCelllndex of SCell with configured uplink is equal to or higherthan 8.

The PHR MAC CEs are defined as follows:

‘Ci field’ indicates the presence of a PH field for the SCell withSCellIndex i. The Ci field set to “1” indicates that a PH field for theSCell with SCellIndex i is reported. The Ci field set to “0” indicatesthat a PH field for the SCell with SCellIndex i is not reported.

‘V field’ indicates if the PH value is based on a real transmission or areference format. For Type 1 PH, V=0 indicates real transmission onPUSCH and V=1 indicates that a PUSCH reference format is used. For Type2 PH, V=0 indicates real transmission on PUCCH and V=1 indicates that aPUCCH reference format is used. For Type 3 PH, V=0 indicates realtransmission on SRS and V=1 indicates that an SRS reference format isused. Furthermore, for Type 1, Type 2, and Type 3 PH, V=0 indicates thepresence of the octet containing the associated P_(CMAX,c) field, andV=1 indicates that the octet containing the associated P_(CMAX,c) fieldis omitted.

‘PH field’ indicates the power headroom level. The length of the fieldis 6 bits. The reported PH and the corresponding power headroom levelsare shown in Table 2.

‘P field’ indicates whether the MAC entity applies power backoff due topower management. The MAC entity shall set P=1 if the correspondingP_(CMAX,c) field would have had a different value if no power backoffdue to power management had been applied.

P_(CMAX,c): if present, this field indicates the P_(CMAX,c) or {tildeover (P)}_(CMAX,c) used for calculation of the preceding PH field. Thereported P_(CMAX,c) and the corresponding nominal UE transmit powerlevels are shown in Table 3

TABLE 3 P_(CMAX, c) Nominal UE transmit power level 0 PCMAX_C_00 1PCMAX_C_01 2 PCMAX_C_02 . . . . . . 61 PCMAX_C_61 62 PCMAX_C_62 63PCMAX_C_63

In NR, the Single Entry PHR MAC CE is identified by a MAC PDU subheaderwith LCID as specified in Table 4. It has a fixed size and consists oftwo octet defined as follows (FIG. 7d ):

TABLE 4 Index LCID values 000000 CCCH 000001-100000 Identity of thelogical channel 100001-110110 Reserved 110111 Configured GrantConfirmation 111000 Multiple Entry PHR 111001 Single Entry PHR 111010C-RNTI 111011 Short Truncated BSR 111100 Long Truncated BSR 111101 ShortBSR 111110 Long BSR 111111 Padding

‘R’ is reserved bit, set to “0”;

Power Headroom (PH) field indicates the power headroom level. The lengthof the field is 6 bits. The reported PH and the corresponding powerheadroom levels are shown in Table 5;

TABLE 5 PH Power Headroom Level 0 POWER_HEADROOM_0 1 POWER_HEADROOM_1 2POWER_HEADROOM_2 3 POWER_HEADROOM_3 . . . . . . 60 POWER_HEADROOM_60 61POWER_HEADROOM_61 62 POWER_HEADROOM_62 63 POWER_HEADROOM_63

P_(CMAX,c) field indicates the P_(CMAX,c) used for calculation of thepreceding PH field. The reported P_(CMAX,c) and the correspondingnominal UE transmit power levels are shown in Table 6.

TABLE 6 P_(CMAX, c) Nominal UE transmit power level 0 PCMAX_C_00 1PCMAX_C_01 2 PCMAX_C_02 . . . . . . 61 PCMAX_C_61 62 PCMAX_C_62 63PCMAX_C_63

The Multiple Entry PHR MAC CE is identified by a MAC PDU subheader withLCID as specified in Table 4. It includes the bitmap, a Type 2 PH fieldand an octet containing the associated P_(CMAX,c) field (if reported)for the PCell, a Type 2 PH field and an octet containing the associatedP_(CMAX,c) field (if reported) for either PSCell or PUCCH SCell, a Type1 PH field and an octet containing the associated P_(CMAX,c) field (ifreported) for the PCell. It further includes, in ascending order basedon the ServCelllndex, one or multiple of Type 1 PH fields and octetscontaining the associated P_(CMAX,c) fields (if reported) for SCellsindicated in the bitmap.

The presence of Type 2 PH field for PCell is configured byphr-Type2PCell, and the presence of Type 2 PH field for either PSCell orfor PUCCH SCell is configured by phr-Type2OtherCell.

A single octet bitmap is used for indicating the presence of PH perSCell when the highest SCellIndex of SCell with configured uplink isless than 8, otherwise four octets are used.

The UE determines whether PH value for an activated Serving Cell isbased on real transmission or a reference format by considering thedownlink control information which has been received until and includingthe PDCCH occasion in which the first UL grant is received since a PHRhas been triggered.

FIG. 7e is an example for Multiple Entry PHR MAC CE with the highestSCellIndex of SCell with configured uplink is less than 8, and FIG. 7fis an example for Multiple Entry PHR MAC CE with the highest SCellIndexof SCell with configured uplink is equal to or higher than 8.

The PHR MAC CEs are defined as follows:

‘Ci field’ indicates the presence of a PH field for the SCell withSCellIndex i. The Ci field set to “1” indicates that a PH field for theSCell with SCellIndex i is reported. The Ci field set to “0” indicatesthat a PH field for the SCell with SCellIndex i is not reported.

‘V field’ indicates if the PH value is based on a real transmission or areference format. For Type 1 PH, V=0 indicates real transmission onPUSCH and V=1 indicates that a PUSCH reference format is used. For Type2 PH, V=0 indicates real transmission on PUCCH and V=1 indicates that aPUCCH reference format is used. For Type 3 PH, V=0 indicates realtransmission on SRS and V=1 indicates that an SRS reference format isused. Furthermore, for Type 1, Type 2, and Type 3 PH, V=0 indicates thepresence of the octet containing the associated P_(CMAX,c) field, andV=1 indicates that the octet containing the associated P_(CMAX,c) fieldis omitted.

‘PH field’ indicates the power headroom level. The length of the fieldis 6 bits. The reported PH and the corresponding power headroom levelsare shown in Table 2 (the corresponding measured values in dB for the NRServing Cell are specified in TS 38.133 while the corresponding measuredvalues in dB for the LTE Serving Cell are specified in TS 36.133).

‘P field’ indicates whether the MAC entity applies power backoff due topower management. The MAC entity shall set P=1 if the correspondingP_(CMAX,c) field would have had a different value if no power backoffdue to power management had been applied.

P_(CMAX,c): if present, this field indicates the P_(CMAX,c) or {tildeover (P)}_(CMAX,c) used for calculation of the preceding PH field. Thereported P_(CMAX,c) and the corresponding nominal UE transmit powerlevels are shown in Table 6 (the corresponding measured values in dB forthe NR Serving Cell are specified in TS 38.133 while the correspondingmeasured values in dB for the LTE Serving Cell are specified in TS36.133).

FIG. 8a is examples for multiple beam pair links, and FIG. 8b is anexample of PHR trigger in BWP activation/deactivation.

To provide link robustness between UE and gNB for both downlink anduplink, there may be multiple beam pair links between UE and gNB, wherea beam pair link comprises a UE TX beam and a gNB RX beam. By using themultiple beam pair links, the UE may be able to transmit or receive adata repeatedly, if necessary. RAN1 agreed that UE should be able tomaintain links with multiple DL beam pair of one cell between multipleTRPs and the UE. For UL link robustness, it would be necessary tomaintain multiple UL beam pair links between multiple TRPs and the UE.In particular, pathloss between multiple TRPs may be significantlydifferent than pathloss in multiple links within a single TRP due totheir locations. This may result in different resource allocations e.g.,including transmit power, between multiple beam pair links. The gNBshould allocate the suitable UL resource for each beam pair based on theUE's PH information. The FIG. 8a describes the examples for multiplebeam pair links.

Meanwhile, similar to the multi-beam case, gNB may have to allocate thesuitable UL resource for each bandwidth part of a UE. To provide avariety of services, NR supports the wider bandwidth composed ofmultiple bandwidth parts with a different numerology. RAN1 agreed thatthe at least one DL bandwidth part and one UL bandwidth part isactivated among the set of configured bandwidth parts for a given timeinstant. Also, RAN1 agreed to primarily focus on the single activebandwidth part case.

Currently, RAN1 has three alternatives to discuss how toactivate/deactivate the DL/UL bandwidth parts, i.e., by means of DCI(Downlink Control Information), RRC signaling or MAC CE. Similar to theCA or DC in LTE, the PHR in NR may be defined to be triggered by the BWPactivation. If the BWPs is activated/deactivated by the DCI, since theBWP activation/deactivation would be dynamically performed by gNB, thePHR transmission will occur very frequently. The FIG. 8b describes anexample of the frequent PHR trigger in case of BWP dynamic activation.In order to prevent the frequent PHR transmissions, we prefer to triggerPHR when the BWPs are configured for a UE. In this case, as eachnumerology may experience different radio condition, PH for differentnumerology would have a different value.

Therefore, for accurate power control, it may be necessary for the UE toreport PHs for all configured numerologies even if the bandwidth partfor the numerology is actually not activated.

FIG. 9 is a conceptual diagram for transmitting a power headroomreporting in wireless communication system according to embodiments ofthe present invention.

When the UE is configured with one or more BWPs per serving cell, the UEtriggers a Power Headroom reporting (PHR) when a BWP is (re)configuration, activation, switching or deactivation (S901).

First, the UE can be a PHR when BWP(s) is (re)configured.

In WB operation, the gNB can configure one or more BWP(s) for a CC ofUE. This means that one or more BWP(s) could be allocated/(re)configuredto a UE while/after gNB activates CC with WB, but before activating thespecific DL/UL BWP. After BWP configuration, the gNB can activate ordeactivate a specific BWP for a UE.

So, our invention proposes to trigger the PHR when BWP(s) of a UE isconfigured by gNB. If the BWP activation/deactivation is indicated bymeans of Downlink Control Information (DCI), i.e., dynamic BWPactivation/deactivation, the PHR may be very frequently triggered sincethe prohibit timer would be independently performed with the PHR triggerevent for BWP activation. So, in case of dynamic BWPactivation/deactivation, it would be preferable that BWP configurationis used for PHR trigger event. If a BWP is configured at the same timeas the serving cell activation, it would be preferable that the PHR istriggered when BWP is reconfigured.

Secondly, the UE can be a PHR when a (Secondary) BWP(s) is activated ordeactivated. In WB operation, the gNB can activate or deactivate one ormore BWP(s) for a UE. This means that a UE can transmit/receive data onthe BWP(s) activated by any indication. So, our invention proposes totrigger the PHR when BWP(s) of a UE is newly activated or deactivated bythe gNB. If a primary BWP is activated at the same time as the servingcell activation, it would be preferable that the PHR is triggered when asecondary BWP is activated.

Lastly, the UE can be a PHR when BWP is switched. In WB operation, thegNB can activate a single BWP for a UE at a given time instant. Thismeans that a UE can transmit/receive data on a single BWP and gNB mayindicate to switch from one BWP to another BWP (or to activate a newBWP) if it needs to activate another BWP. The purpose of the BWPswitching command is to change an active BWP used in a particular cell.That is, the BWP switching command is for switching active BWP.

Currently, the UE is configured with four BWPs per cell, and only one ofthem will be in active state. When a BWP switching command is receivedvia DCI, the UE deactivates the active BWP and activates the new BWPautonomously (i.e, there is no BWP deactivation command). Our inventionproposes to trigger the PHR when a BWP of UE is switched to another BWPby gNB.

When the PHR is triggered, the UE generates a Power Headroom Reporting(PHR) Medium Access Control (MAC) Control Element (CE) includingmultiple PH fields for a serving cell, and an octet containing a singleP_(CMAX) field associated with the multiple PH fields for the servingcell (S903). And the UE transmits the PHR MAC CE to a network (S905).

For example, in a state that the gNB configures a component carrier(e.g., SCell) with wider bandwidth for UE, the gNB (re)configures one ormore BWPs for UE during or after SCell activation. When BWPs are(re)configured by gNB, the UE transmits PHR including PH information forconfigured BWPs (B₀, B₁).

For the deactivated B₁, the UE can calculate the PH value based on thereference format. For the activated B₀, the UE can calculate the PHvalue based on a real transmission.

Although the gNB activates or deactivates a configured BWP for a UE, theUE transmits the PHR only when a PHR trigger event is met, e.g., PHRperiodic timer expiry, pathloss changes more than threshold after PHRprohibit timer expiry, configuration of PHR functionality, Scellactivation, PSCell addition, etc.

FIG. 10 is an example of PHR trigger based on the BWP configuration.

Although only BWP is described, beam pair can be applied similarly.

When the UE is configured with one or more BPs per serving cell, the UEtriggers a Power Headroom reporting (PHR) when a BP is (re)configuration, activation, switching or deactivation (S901).

First, the UE can be a PHR when BP(s) is (re)configured.

In multiple beam operation, the gNB can configure one or more BP(s) fora CC of UE. This means that one or more BP(s) could beallocated/(re)configured to a UE while/after gNB activates CC withmulti-beam, but before activating the specific DL/UL BP. After BPconfiguration, the gNB can activate or deactivate a specific BP for aUE.

So, our invention proposes to trigger the PHR when BP(s) of a UE isconfigured by gNB. If the BP activation/deactivation is indicated bylower layer, the PHR may be very frequently triggered since the prohibittimer would be independently performed with the PHR trigger event for BPactivation. If a BP is configured at the same time as the serving cellactivation, it would be preferable that the PHR is triggered when BP isreconfigured.

Secondly, the UE can be a PHR when a BP(s) is activated or deactivated.In multi beam operation, the gNB can activate or deactivate one or moreBP(s) for a UE. This means that a UE can transmit/receive data on theBP(s) activated by any indication. So, our invention proposes to triggerthe PHR when BP(s) of a UE is newly activated or deactivated by the gNB.

Lastly, the UE can be a PHR when BP is switched. In multi beamoperation, the gNB can activate a single BP for a UE at a given timeinstant. This means that a UE can transmit/receive data on a single BPand gNB may indicate to switch from one BP to another BWP (or toactivate a new BP) if it needs to activate another BP. Our inventionproposes to trigger the PHR when a BP of UE is switched to another BP bygNB.

When the PHR is triggered, the UE generates a Power Headroom Reporting(PHR) Medium Access Control (MAC) Control Element (CE) includingmultiple PH fields for a serving cell, and an octet containing a singleP_(CMAX) field associated with the multiple PH fields for the servingcell (S903). And the UE transmits the PHR MAC CE to a network (S905).

For example, in a case that the UE performs the beam management, the gNBconfigures one or more UL beam pair (i.e., UE Tx beam and gNB Rx beam)for a UE. This beam management can include beam measurement andreporting the measurement results.

The gNB can allocate the UL resources for multi-BP of a UE. Theresources would be time domain multiplexed.

When one or more UL beam pair is (re)allocated/activated by gNB and PHRtrigger event is met, the UE transmits PHR including PH information foractivated BPs (B₀, B₁).

At the time instant of PHR transmission, for the B₁ without theallocated UL resource, the UE can calculate the PH value based on thereference format. At the time instant of PHR transmission, for the B₀with the allocated UL resource, the UE can calculate the PH value basedon a real transmission.

Theses formats A to C, described in detail below, are used in a casewhere multiple bandwidth parts are configured to a UE and the bandwidthpart is dynamically activated/deactivated by DCI, or another case whereUL multiple beam pairs are allocated to a UE and the resources fordifferent UL BPs are multiplexed in the time domain.

FIGS. 11 and 12 are examples for a PHR MAC CE for BP or BWP operation(format A) according to embodiments of the present invention.

This invention proposes that a UE transmits one or more PH(s) for asingle P_(CMAX, C) field in PHR MAC CE in order to inform each PH fordifferent UL beam pair (hereinafter, referred to as BP) or differentnumerology/bandwidth part (hereinafter, referred to as BWP) of a servingcell.

In particular, this invention proposes to define a new PHR MAC CE formatincluding an octet containing a single P_(CMAX) field associated withthe multiple PH fields for the serving cell.

In this case, the single P_(CMAX) field is used for calculation of thepreceding multiple PH fields.

The PH information for each BP/BWP can mean P, V and PH value for TypeX.

Preferably, in this case, the multiple PH fields are a same type of PH.

This format A proposes to define a PH bitmap per serving cell toindicate whether at least two PH information for different BP/BWP arepresent or not. The PH bitmap for a specific Ci is present if the Cifield is set to 1. That is the PH bitmap is present when the servingcell is activated.

The PH bitmap for the primary cell may be always located after the octetcontaining Ci fields (Ci bitmap) or the indication bit (C₀) for PCellmay be defined to indicate whether PH bitmap of PCell is present or not.

Here, we assume that the maximum number of the configured ULBP(s)/BWP(s) is set to j and the length of each PH bitmap is defined toj (or j−1) bits, where j is an integer value greater than zero.

If the bit (Bj) corresponding to a certain BP/BWP index is set to 1, PHinformation for the BP/BWP are transmitted by UE. If Bj field is set to1, in descending or ascending order of the Bj set to 1, corresponding PHinformation are defined before the P_(CMAX, C).

If Ci field is set to 1, in descending or ascending order of the Ci setto 1, corresponding PH bitmap follows after the Ci bitmap, as shown inthe FIG. 11.

Alternatively, if Ci field is set to 1, the PH bitmap for the servingcell follows before the first PH information of the serving cell asshown in the FIG. 12.

In addition, if Ci field is set to 1, the PH bitmap for the serving cellcan follow right after each Ci. The PH bitmap can be located in avariety of ways not described here.

Here, the indication bit (B₀) for the primary BP/BWP of each cell can beomitted since the primary BP/BWP may be always present if the servingcell is present.

Format A benefits that the processing can be performed more efficientlyat the receiving end, since the proposed PHR MAC CE includes an octetcontaining the BWP bitmap is included first after an octet containingthe Ci bitmap and followed by an octet containing PH information.Further, Format A reports all of the active BWP PHs for the active cell,so it is advantageous for the base station to know the PH of each BWPaccurately.

FIG. 13 is an example for a PHR MAC CE for BP or BWP operation (formatB) according to embodiments of the present invention.

This Format B proposes that a UE transmits the configured/fixed numberof PH information for each serving cell. Here, the PH informationconsists of P, V and PH for type x.

Since every serving cell may not consist of more than one BP/BWP, inorder to reduce the signalling overhead, we also propose to define thePH bitmap (PBi) to indicate whether two or more PH information for theserving cell (Ci) are present or not.

That is, when the number of PH that can be reported for a certainserving cell is fixed to a specific value, the PH bitmap is alwayslocated after the octet containing Ci fields (Ci bitmap) and a length ofthe PH bitmap is equal to a number of configured serving cells, e.g.,based on LTE, the length of PH bitmap can be 8 or 32.

If the Ci bit for the serving cell is set to 1, the gNB should checkwhether the corresponding Bi bit is set to 1 or 0. Based on LTE, gNBwould always check the indication bit (PB0) for the primary cell. If thecorresponding PBi bit is also set to 1, the fixed number (j, where j isan integer value greater than zero) of PHs are defined in the PH sectionfor the serving cell as described in FIG. 13.

From a UE perspective, if a UE needs to inform at least two PHs for acertain serving cell, the UE should set the Ci and PBi bit correspondingto the serving cell and contain PH list for the configured BP/BWPs andone P_(CMAX, c) for the serving cell.

The each PH for a BP/BWP can be located in a variety of rules notdescribed here.

The Format B is useful when the number of multiple PHs that can bereported for a serving cell is fixed, because the PHR MAC CE containsone octet containing the Bi field, thereby reducing signal overhead.

FIG. 14 is an example for a PHR MAC CE for BP or BWP operation (formatC) according to embodiments of the present invention.

The format C proposes to newly define BP/BWP index field in the PHR MACCE.

This scheme proposes to define BP/BWP index field in the PHR MAC CE, ifan additional PH information for a serving cell is present. If the gNBneeds to know whether the additional PH information for each BP/BWP ispresent or not, it also proposes to define a PH extension field in thePHR MAC CE.

The PH extension field indicates whether an additional PH informationwith BP/BWP index is present or not. It will be 1-bit length.

If the PH extension is set to 1, an additional PH with the BP/BWP indexis transmitted by UE. Here, we assume that the length of a BP/BWP indexcan be defined to j bits according to the maximum number of theconfigured BP/BWP, where j is an integer value greater than zero.

The PH extension field can be defined using the reserved bit before eachP_(CMAX, c) and after/before the BP/BWP index, as shown in the FIG. 14.

If the PH extension filed is set to 1, the BP/BWP index andcorresponding PH information are included after the P_(CMAX,c) field forthe cell. The proposed PH extension and BWP index can be located in avariety of ways not described here.

Format C is advantageous in a cased that the UE is configured with manyBWPs per cell (e.g, a 4-bit or 8-bit bitmap or longer BWP bitmap fieldis needed). That is, there is an advantage in view of transmissionoverhead.

The PHR triggered by the new triggering events described above may usethe new PHR MAC CE proposed in formats A to C of the present inventions.

Since the value of P_(CMAX,c) field may be dependent on a serving cell,it is likely that it will have the same P_(CMAX,c) value even if thereare several BPs or several BWPs in the serving cell. The presentinvention can be usefully used in such cases. According to the presentinvention, since one P_(CMAX,c) is used for calculation of multiple PHinformation, the reporting amount of the PHR MAC CE can be reduced.

The embodiments of the present invention described hereinbelow arecombinations of elements and features of the present invention. Theelements or features may be considered selective unless otherwisementioned. Each element or feature may be practiced without beingcombined with other elements or features. Further, an embodiment of thepresent invention may be constructed by combining parts of the elementsand/or features. Operation orders described in embodiments of thepresent invention may be rearranged. Some constructions of any oneembodiment may be included in another embodiment and may be replacedwith corresponding constructions of another embodiment. It is obvious tothose skilled in the art that claims that are not explicitly cited ineach other in the appended claims may be presented in combination as anembodiment of the present invention or included as a new claim bysubsequent amendment after the application is filed.

In the embodiments of the present invention, a specific operationdescribed as performed by the BS may be performed by an upper node ofthe BS. Namely, it is apparent that, in a network comprised of aplurality of network nodes including a BS, various operations performedfor communication with an MS may be performed by the BS, or networknodes other than the BS. The term ‘eNB’ may be replaced with the term‘fixed station’, ‘Node B’, ‘Base Station (BS)’, ‘access point’, etc.

The above-described embodiments may be implemented by various means, forexample, by hardware, firmware, software, or a combination thereof.

In a hardware configuration, the method according to the embodiments ofthe present invention may be implemented by one or more ApplicationSpecific Integrated Circuits (ASICs), Digital Signal Processors (DSPs),Digital Signal Processing Devices (DSPDs), Programmable Logic Devices(PLDs), Field Programmable Gate Arrays (FPGAs), processors, controllers,microcontrollers, or microprocessors.

In a firmware or software configuration, the method according to theembodiments of the present invention may be implemented in the form ofmodules, procedures, functions, etc. performing the above-describedfunctions or operations. Software code may be stored in a memory unitand executed by a processor. The memory unit may be located at theinterior or exterior of the processor and may transmit and receive datato and from the processor via various known means.

Those skilled in the art will appreciate that the present invention maybe carried out in other specific ways than those set forth hereinwithout departing from essential characteristics of the presentinvention. The above embodiments are therefore to be construed in allaspects as illustrative and not restrictive. The scope of the inventionshould be determined by the appended claims, not by the abovedescription, and all changes coming within the meaning of the appendedclaims are intended to be embraced therein.

INDUSTRIAL APPLICABILITY

While the above-described method has been described centering on anexample applied to the 3GPP LTE and NR system, the present invention isapplicable to a variety of wireless communication systems in addition tothe 3GPP LTE and NR system.

1. A method for a User Equipment (UE) operating in a wirelesscommunication system, the method comprising: generating a Power HeadroomReporting (PHR) Medium Access Control (MAC) Control Element (CE)including multiple Power Headroom (PH) fields for a serving cell; andtransmitting the PHR MAC CE, wherein the PHR MAC CE includes an octetcontaining a single P_(CMAX) field associated with the multiple PHfields for the serving cell.
 2. The method according to claim 1, whereinthe multiple PH fields associated with the single P_(CMAX) field are asame type of PH.
 3. The method according to claim 1, wherein the UEoperates in multiple-beam operation or multiple-Bandwidth Part (BWP)operation.
 4. The method according to claim 3, wherein the PHR MAC CEincludes a Beam Pair (BP) or Bandwidth Part (BWP) bitmap indicatingpresence of a PH field per BP or BWP within the serving cell, andwherein the BP or BWP bitmap includes one or more fields, each of theone or more fields corresponding to a respective BP or BWP with an indexj, and indicating presence of a PH field for the respective BP or BWPidentified by the index j.
 5. The method according to claim 3, whereinthe PHR MAC CE includes a BP or BWP index field indicating BP or BWPinformation corresponding to a PH field in the PHR MAC CE, wherein whenthe PHR MAC CE includes the BP or BWP index field, the PHR MAC CEfurther includes a PH extension field indicating whether an PHinformation corresponding to the BP or BWP index is present or not. 6.The method according to claim 1, further comprising: triggering a PHRfor generating the PHR MAC CE when one of followings: a BWP is newlyconfigured, or a configured BWP is activated or deactivated, or aconfigured BWP is switched, when the UE operates in multiple-BandwidthPart (BWP) operation.
 7. The method according to claim 1, furthercomprising: triggering a PHR for generating the PHR MAC CE when one offollowings: a BP is newly configured, or a configured BP is activated ordeactivated, or a configured BP is switched, when the UE operates inmulti-beam operation.
 8. The method according to claim 1, wherein thesingle P_(CMAX) field includes power information used for calculation ofthe associated multiple PH fields.
 9. A User Equipment (UE) foroperating in a wireless communication system, the UE comprising: a RadioFrequency (RF) module; and a processor operably coupled with the RFmodule and configured to: generate a Power Headroom Reporting (PHR)Medium Access Control (MAC) Control Element (CE) including multiplePower Headroom (PH) fields for a serving cell, and transmit the PHR MACCE, wherein the PHR MAC CE includes an octet containing a singleP_(CMAX) field associated with the multiple PH fields for the servingcell.
 10. The UE according to claim 9, wherein the multiple PH fieldsassociated with the single P_(CMAX) field are a same type of PH.
 11. TheUE according to claim 9, wherein the UE operates in multiple-beamoperation or multiple-Bandwidth Part (BWP) operation.
 12. The UEaccording to claim 11, wherein the PHR MAC CE includes a Beam Pair (BP)or Bandwidth Part (BWP) bitmap indicating presence of a PH field per BPor BWP within the serving cell, and wherein the BP or BWP bitmapincludes one or more fields, each of the one or more fieldscorresponding to a respective BP or BWP with an index j, and indicatingpresence of a PH field for the respective BP or BWP identified by theindex j.
 13. The UE according to claim 11, wherein the PHR MAC CEincludes a BP or BWP index field indicating BP or BWP informationcorresponding to a PH field in the PHR MAC CE, wherein when the PHR MACCE includes the BP or BWP index field, the PHR MAC CE further includes aPH extension field indicating whether an PH information corresponding tothe BP or BWP index is present or not.
 14. The UE according to claim 9,wherein the processor is further configured to: trigger a PHR forgenerating the PHR MAC CE when one of followings: a BWP is newlyconfigured, or a configured BWP is activated or deactivated, or aconfigured BWP is switched, when the UE operates in multiple-BandwidthPart (BWP) operation.
 15. The UE according to claim 9, wherein theprocessor is further configured to: trigger a PHR for generating the PHRMAC CE when one of followings: a BP is newly configured, or a configuredBP is activated or deactivated, or a configured BP is switched, when theUE operates in multi-beam operation.
 16. The UE according to claim 9,wherein the single P_(CMAX) field includes power information used forcalculation of the associated multiple PH fields.
 17. The methodaccording to claim 1, wherein the UE is capable of communicating with atleast one of another UE, a UE related to an autonomous driving vehicle,a base station and/or a network.
 18. The UE according to claim 9,wherein the UE is capable of communicating with at least one of anotherUE, a UE related to an autonomous driving vehicle, a base station and/ora network.